Electrodeposition of copper



nited States 2,814,590 ELECTRODEPOSITION OF COPPER Lloyd B. Portzer,Cleveland, and William C. Leitenherger, Rocky River, Ohio No Drawing.Application July 20, 1954, Serial No. 444,644 16 Claims. (Cl. 204-52)hydroxide and Rochelle salts, which operate to produce a free cyanide.

In recent years, copper, electrodeposited from Rochellecyanide solutionshas found increasing application in the field of electroplating. Incertain commercial applications, it has been found that a thin strike ofcopper will impart better overall characteristics to the resultantproduct that is being produced. For example, in the application ofnickel by electrolysis, to steel, it has been found that a copper strikeon the order of 0.001 inch will give better protection than when theelectrodeposited nickel is applied directly to the steel. Recently, ithas been necessary to apply a preliminary deposit of copper to conservethe amount of nickel that is used in the production of an electroplatedpart. A still further factor contributing to the increased usage ofcopper lies in the fact that the same can be employed as anelectrodeposit on certain metals that would not otherwise satisfactorilyreceive a plated deposit. For example, in the field of electroplatingdie-castings it has been discovered that the acid present in the nickelelectrolyte attacks the surface of the die-casting and accordingly,renders the electroplating thereof unsatisfactory. Such a condition doesnot exist, however, with regard to the electroplating of diecastings inRochelle-cyanide solutions.

It has been discovered in the filed of plating, that the brightness orlustre of the electroplated surface is directly affected by thebrightness of the undercoat employed. This fact motivated thedevelopment of bright nickel plating, and has stimulated the recentefforts to increase the brightness of electrodeposited copper.

These efforts at increasing the lustre of the copper deposit havefollowed the pattern employed in bright nickel plating and accordingly,have been directed toward the use of addition agents that would operateto brighten the bath. These addition agents have been both organic andinorganic in nature, but have met with limited acceptability due totheir inherent insolubility in the Rochellecyanide solution. Lead andselenium compounds, for example, while possessing brightening propertiesin baths other than copper, have heretofore met With limited success inRochelle-cyanide solutions because of their limited solubility insolution, especially over an extended period of time. This limitedsolubility, which may be expressed in terms of instability, curtails theusefulness of these compounds.

Accordingly, it is one object of this invention to provide improvedtypes of addition agents that are characterized by substantiallyindefinite stability, as well as being possessed of brighteningproperties.

It is a further object of this invention to provide a 2,83%,59 PatentedNov. 26,

method for converting insoluble addition agents into addition agentspossessing the property of stability in Rochelle solutions.

It is a still further object of this invention to provide aRochelle-cyanide solution that has been modified to permit receptiontherein of normally unstable addition agents.

These and other objects of the invention will become more apparent upona reading of the following brief specification.

It has been discovered that many organic and inorganic compounds, thatpossess brightening properties but are normally unstable in Rochelleplating solutions, can be converted into stable compounds by beingadmixed with certain reaction products of aliphatic amines.

Specifically, it has been discovered that if an aliphatic amine isreacted with an alkaline metal cyanide in the presence of aformaldehyde-yielding substance, the resulting reaction product willfurther react with normally insoluble compounds to convert the same intosoluble compounds having brightening properties in a Rochelle solution.This reaction product may be produced in one of two ways.

First, employing the teachings of Bersworth U. S. Patent 2,407,645, asolution of free unreacted aliphatic amine and alkali metal cyanide issubjected to the addition of formaldehyde. Basically, this patentteaches the reacting of an aliphatic amine having at least onereplaceable hydrogen atom attached directly to an amino nitrogen atom,with an alkali metal cyanide formaldehyde-yielding substance underconditions sufficiently alkaline that there is substantially nohydrolysis of said cyanide and in total amounts such that for eachreplaceable hydrogen atom one molecule of said cyanide and one moleculeof said formaldehyde substance are added during the reaction. Followingthe teachings of Example 2, it is possible to produce a compound knownas ethylene diamine tetracetic acid having the below-listed formula.

The sodium salt of the above compound, it is believed, operates tochelate or inactivate certain metallic ions by absorbing the same in thering structure thereof. This reaction prevents the precipitationcharacteristic of insolubility, and accordingly, these metallic ions areinactivated against precipitation. A typical such reaction is listedbelow.

The second method of producing this preferred reaction product abovedescribed, comprises addition of an aliphatic amine to a Rochellesolution that is characterized by an excess of free cyanide of thealkali metal type. Such cyanide exists in Rochelle plating baths in theform of potassium or sodium cyanide and it is theorized that thesecondary reactions occurring in the plating bath upon the addition ofthe aliphatic amine operate to produce formaldehyde type substance thatcompletes the requisite reaction product. In this regard, it is a wellknown fact, in the electrodeposition of copper from Rochelle-cyanidesolutions, that such solutions possess a certain amount of formic, ormethanoic acid (HCOOOH) It is entirely possible and within the realm ofprobability that the subject formic acid is reacted during the complexsecondary actions that occur during electroylsis. to form formaldehyde.Thus, it can be seen that the conventional Rochelle-cyanide solutioncontains the necessary compounds that are capable of reacting with addedaliphatic amines to produce the reaction product that is the subject ofthis invention. As will be observed from the examples that aresubsequently set forth, several aliphatic amines have operated withresults equivalent to those obtained by using the pre-preparedpolycarboxylic amino acids of the Bersworth patent. Accordingly, it isconcluded that the reaction product of any aliphatic amine with analkali metal cyanide will operate to produce a compound having thefollowing representative formula:

where X is an organic radical or hydrogen R and R1 are the same ordifferent organic radical Y is an alkali metal or hydrogen.

In the below-listed examples, there is illustrated the use of variousreaction products of aliphatic amines and alkali metal cyanides that areused in conjunction with certain compounds of selenium and lead. Thesecompounds are believed representative of a wide range of chemicalcompounds whose use can be improved by combination with any one ofseveral such improved reaction products indicated above.

EXAMPLE 1 Without the aid of heat and by agitation only, .21 gram ofselenium dioxide was dissolved in 25 cc. of N- butylamine and 25 cc.distilled H20.

EXAMPLE 2 Without the aid of heat and by agitation only, .21 gram ofselenium dioxide were dissolved in 25 cc. of ethylene diamine and 25 cc.of distilled H2O.

EXAMPLE 3 Without the aid of heat and by agitation only, .21 gram ofselenium dioxide were dissolved in 25 cc. of Nullapson B. F. acid(ethylene diamine tetracetic acid, powder) and 25 cc. of distilled H2O.

EXAMPLE 4 Without the aid of heat and by agitation only, .26 gram oflead carbonate were dissolved in 25 cc. of N- butylamine and 25 cc. ofdistilled H20.

EXAMPLE 5 Without the aid of heat and by' agitation only, .26

4 gram of lead carbonate were dissolved in 25 cc. of ethylene diamineand 25 cc. of distilled H2O.

EXAMPLE 6 Without the aid of heat and by agitation only, .26 gram oflead carbonate were dissolved in 25 cc. of Nullapson B. F. acid(ethylene diamine tetracetic acid, powder) and 25 cc. of distilled H2O.

EXAMPLE 7 Without the aid of heat and by agitation only, 30 grams ofselenium dioxide were dissolved in 300 cc. of Versene T (the sodium saltof ethylene diamine tetracetic acid) and water to make one gallon ofsolution.

EXAMPLE 8 Without the aid of heat and by agitation only, 10 grams oflead carbonate were dissolved in 1000 cc. of Versene T (the sodium saltof ethylene diamine tetracetic acid) and water to make one gallon ofsolution.

With the above liquids prepared as indicated, Hull cell panels were madeusing the solutions of Examples 9, 10, 11 and 12. A current of 3 ampswas employed in the Hull cell resulting in a theoretical current densityof 0-l25 amps per sq. ft.

EXAMPLE .9

Cc. Rochelle solution 1 400 Addition agent per Example 1 u 4 Additionagent per Example 4 1 EXAMPLE l0 Rochelle solution 400 Addition agentper Example 2 4 Addition agent per Example 5 1 EXAMPLE l1 Rochellesolution 400 Addition agent per Example 3 4 Addition agent per Example 61 EXAMPLE 12 Rochelle solution 400 Addition agent per Example 9 4Addition agent per Example 10 1 The chemical composition of the Rochellesolution employed in Examples 9, 10, 11 and 12 was as follows: Coppercyanide 6.73 oz. per gal. (4.77 oz. per 1 gal. of pure copper byanalysis) free potassium cyanide 1.25 oz. per gal; caustic potassium 3.0oz. per gal; Rochelle salts 6.66 oz. per gal.

The panels obtained from the use of the solutions described were allcharacterized by extreme brightness of a wide current density range. Thesolutions of Examples 9, l0, l1 and 12 were then allowed to stand forapproximately two weeks and at that time a second set of panels weremade from these respective solutions. All of the panels possessedequivalent lustre to the panels originally plated from the respectivesolutions, thus indicating that the selenium and lead were stillstabilized in the addition agent to the extent that the same couldfuncion to impart brightness upon being subsequently introduced into aRochelle solution.

While the above examples have illustrated the invention in connectionwith the use of certain selected selenium and lead compounds, it is tobe understoodthat these compounds are merely representative, andaccordingly, similar selenium and lead compounds could be substituted inthe foregoing examples, provided the game were soluble with respect tothe reacted aliphatic amino and. did not produce a detrimental elfect onthe plating bath. Accordingly, in. Table A. listed below, certainadditional compounds, submitted to meet the aforementioned'requirements: are set forth.

By like token, it is manifest that the improved reaction products of analiphatic amine do not have to be reacted With the selenium or leadcompounds prior to introduction to the Rochelle solution. In this regardit has been found that if the Rochelle solution is treated with anexcess of these reaction products, addition agents, such as seleniumdioxide and lead carbonate, will remain stable in the addition agentsemployed, and thus can effectively operate in a Rochelle solution toproduce a bright copper deposit.

Similarly, while a specific Rochelle solution has been set forth inconnection with Examples 9-12 inclusive, it is to be understood that therange of the respective constituents thereof can be varied within knownlimits of commercial practice, and accordingly, the disclosure is notlimited to the Rochelle solution set forth. Additionally, while Examples9 to 12 inclusive, recite the use of two addition agents, it is to bespecifically understood that the stability of any one addition agent inthe Rochelle solution is not predicated upon the use of a secondaddition and accordingly, any one addition agent of Examples 1 to 8could be employed alone with a Rochelle solution with the equivalentresult that the selenium or lead compound is stabilized in the Rochellesolution.

It is also to be noted that the operation of the aforementioned reactionproduct with lead and selenium compounds is no way predicated upon theuse of Rochelle salts in the plating bath. Accordingly, the use ofRochelle salts may be eliminated and citrates or tartrates substitutedtherefore in known manner. By like token, a sodium cyanide electrolytecould be utilized in place of the potassium solution illustrated inconjunction with Examples 9 to 12 inclusive.

It will be seen from the foregoing that there has been provided a newand novel method of increasing the stability and useability of certainheretofore unstable brightening compounds for plating baths by reactingthe same with certain novel reaction products. It has been shown how theuse of these novel reaction products operates to increase the lustre andductility of an electrodeposit from a Rochelle-cyanide solution, andaccordingly, effectuates a savings in time and money as well asresulting in the improvement of the end product. It has also been shownhow these improved reaction products can be added to the bath, eitherseparately or with other addition agents, thus increasing the overallutility of the same.

Accordingly, modifications of the invention may be resorted to withoutdeparting from the spirit thereof or the scope of the appended claims.

-What is claimed is:

1. A bath for the electrodeposition of copper, comprising copper cyanidein concentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations ranging from 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; and a seleniumchelate; said selenium chelate being the product resulting from thereaction of a soluble selenium compound with the reaction productobtained by reacting an aliphatic amine having at least one replaceablehydrogen atom attached directly to an amino nitrogen atom with an alkalimetal cyanide and a formaldehydeyielding substance under conditionssufliciently alkaline that there is substantially no hydrolysis of saidcyanide and in total amounts such that for each replaceable hydrogenatom one molecule of said cyanide and one molecule of said formaldehydesubstance are added during the reaction; said selenium chelate beingpresent in solution in excess of .1 gram per gallon of solution andbeing without valence.

2. A bath for the electrodeposition of copper, comprising copper cyanidein concentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations ranging from 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; and a lead chelate;said lead chelate being the product resulting from the reaction of asoluble lead compound with the reaction product obtained by reacting analiphatic amine having at least one replaceable hydrogen atom attacheddirectly to an amino nitrogen atom with an alkali metal cyanide and aformaldehyde-yielding substance under conditions sufficiently alkalinethat there is substantially no hydrolysis of said cyanide and in totalamounts such that for each replaceable hydrogen atom one molecule ofsaid cyanide and one molecule of said formaldehyde substance are addedduring the reaction; said lead chelate being present in solution inexcess of .01 gram per gallon of solution and being without valence.

3. A bath for the electrodeposition of copper, comprising copper cyanidein concentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations ranging from 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; a selenium chelate;said selenium chelate being the product resulting from the reaction of asoluble selenium compound with the reaction product obtained by reactingan aliphatic amine having at least one replaceable hydrogen atomattached directly to an amino nitrogen atom with an alkali metal cyanideand a formaldehyde-yielding substance under conditions sufficientlyalkaline that there is substantially no hydrolysis of said cyanide andin total amounts such that for each replaceable hydrogen atom onemolecule of said cyanide and one molecule of said formaldehyde substanceare added during the reaction; and a lead chelate; said lead chelatebeing the product resulting from the reaction of a soluble lead compoundwith the reaction product obtained by reacting an aliphatic amine havingat least one replaceable hydrogen atom attached directly to an aminonitrogen atom with an alkali metal cyanide and a formaldehydeyieldingsubstance under conditions sufficiently alkaline that there issubstantially no hydrolysis of said cyanide and in total amounts suchthat for each replaceable hydrogen atom one molecule of said cyanide andone molecule of said formaldehyde substance are added during thereaction; said selenium chelate being present in solution in excess of.1 gram per gallon of solution and being without valence; said leadchelate being present in solution in excess of .01 gram per gallon ofsolution and being without valence.

4. A bath for the electrodeposition of copper, comprising; coppercyanide in concentrations ranging from 2.5 to 16.0 oz. per gallon ofsolution; potassium cyanide in concentrations ranging from 3.5 to 25.0oz. per gallon of solution; potassium hydroxide in concentrationsranging from 2.0 to 8.0 oz. per gallon of solution; Rochelle salts inconcentrations ranging from 3.0 to 12.0 oz. per gallon of solution; anda selenium chelate; said selenium chelate being the product resultingfrom the reaction of a soluble selenium compound with ethylene diaminetetracetic acid; said selenium chelate being present in solution inexcess of .1 gram per gallon of solution and being without valence. 5. Abath for the electrodeposition of copper, comprising; copper cyanide inconcentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations ranging from 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; and a seleniumchelate; said selenium chelate being the product resulting from thereaction of selenium dioxide with ethylene diamine tetracetic acid; saidselenium chelate being present in solution in excess of .1 gram pergallon of solution and being without valence.

6. A bath for the electrodeposition of copper, comprising copper cyanidein concentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations ranging from 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; and a lead chelate;said lead chelate being the product resulting from the reaction of asoluble lead compound With ethylene diamine tetracetic acid; said leadchelate being present in solution in excess of .01 gram per gallon ofsolution and being Without valence.

7. A bath for the electrodeposition of copper, comprising copper cyanidein concentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations ranging from 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; and a lead chelate;said lead chelate being the product resulting from the reaction of leadcarbonate with ethylene diamine tetracetic acid; said lead chelate beingpresent in solution in excess of .01 gram per gallon of solution andbeing without valence.

8. A bath for the electrodeposition of copper, comprising copper cyanidein concentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations rangingfrom 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; a selenium chelate;said selenium chelate being the product resulting from the reaction of asoluble selenium compound with ethylene diamine tetracetic acid; and alead chelate; said lead chelate being the product resulting from thereaction of a soluble lead compound with ethylene diamine tetraceticacid; said selenium chelate being present in solution in excess of .1grain per gallon of solution and being without valence; said leadchelate being present in solution in excess of .01 gram per gallon ofsolution and being without valence.

9. A bath for the electrodeposition of copper, comprising copper cyanidein concentrations ranging from 2.5 to 16.0 oz. per gallon of solution;potassium cyanide in concentrations ranging from 3.5 to 25.0 oz. pergallon of solution; potassium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; a selenium chelate;said selenium chelate being the product resulting .from the reaction ofselenium dioxide with ethylene diamine tetracetic acid; and a leadchelate; said lead chelate being the product resulting from the reactionof lead carbonate with ethylene diamine tetracetic acid; said seleniumchelate being present in solution in excess of .1 gram per gallon ofsolution and being without valence; said lead chelate being present insolution in excess of .01 gram per gallon of solution and being withoutvalence.

10. A bath for the electrodeposition of copper, comprising coppercyanide in concentrations ranging from 2.5 to 16.0 oz. per gallon ofsolution; sodium cyanide in concentrations ranging from 3.5 to 25.0 oz.per gallon of solution; sodium hydroxide in concentrations ranging from2.0 to 8.0 oz. per gallon of solution; Rochelle salts in concentrationsranging from 3.0 to 12.0 oz. per gallon of solution; a selenium chelate;said selenium chelate ing the product resulting from the reaction ofselenium dioxide with ethylene diamine tetracetic acid; and a leadchelate; said lead chelate being the product resulting from the reactionof lead carbonate with ethylene diamine tctracetic acid; said seleniumchelate being present in solution in excess of .1 gram per gallon ofsolution and being without valence; said lead chelate being present insolution in excess of .01 gram per gallon of solution and being Withoutvalence.

11. A method of electrodepositing copper, comprising the step ofelectrolyzing a Rochelle copper cyanide solution containing a seleniumchelate; said selenium chelate being the product resulting from thereaction of a soluble selenium compound and ethylene diamine tetraceticacid; said selenium chelate being present in solution in concentrationsexceeding .1 gram per gallon of solution.

12. A method of electrodepositing copper, comprising the step ofelectrolyzing a Rochelle copper cyanide solution containing a leadchelate; said lead chelate being the product resulting from the reactionof a soluble lead compound and ethylene diamine tetracetic acid; saidlead chelate being present in solution in concentrations exceeding .01gram per gallon of solution.

13. A method of electrodepositing copper, comprising the step ofelectrolyzing a Rochelle copper cyanide solution containing a seleniumchelate and a lead chelate; said selenium chelate being the productresulting from the reaction of a soluble selenium compound and ethylenediamine tetracetic acid; said selenium chelate being present in solutionin concentrations exceeding .1 gram per gallon of solution; said leadchelate being the product resulting from the reaction of a soluble leadcompound and ethylene diamine tetracetic acid; said lead chelate beingpresent in solution in concentration exceeding .01 gram per gallon ofsolution.

14. A method of electrodepositing copper, comprising the step ofelectrolyzing a Rochelle copper cyanide solution containing a seleniumchelate; said selenium chelate being the product resulting from thereaction of a soluble selenium compound and the reaction productobtained by reacting an aliphatic amine having at least one replaceablehydrogen atom attached directly to an amino nitrogen atom with an alkalimetal cyanide and a formaldehydeyielding substance under conditionssufficiently alkaline that there is substantially no hydrolysis of saidcyanide and in total amounts such that for each replaceable hydrogenatom one molecule of said cyanide and one molecule of said formaldehydesubstance are added during the reaction; said selenium chelate beingpresent in solution in concentrations exceeding .1 gram per gallon ofsolution.

15. A method of electrodepositing copper, comprising the step ofelectrolyzing a Rochelle copper cyanide solution containing a leadchelate; said lead chelate being the product resulting from the reactionof a soluble lead compound and the reaction product obtained by reactingan aliphatic amine having at least one replaceable hydrogen atomattached directly to an amino nitrogen atom with an alkali metal cyanideand a formaldehyde-yielding substance under conditions sufficientlyalkaline that there is substantially no hydrolysis of said cyanide andin total amounts such that for each. replaceable hydrogen atom onemolecule of said cyanide and one molecule of said formaldehyde substanceare added during the reaction; said lead chelate being present insolution in concentrations exceeding .01 gram per gallon of solution.

16. A method of electrodepositing copper, comprising the step ofelectrolyzing a Rochelle copper cyanide solution containing a seleniumchelate and a lead chelate; said selenium chelate being the productresulting from the reaction of a soluble selenium compound and thereaction product obtained by reacting an aliphatic amine having at leastone replaceable hydrogen atom attached directly to an amino nitrogenatom with an alkali metal cyanide and a formaldehyde-yielding substanceunder conditions sufficiently alkaline hydrolysis of said cyanide and intotal amounts such that for each replaceable hydrogen atom one moleculeof said cyanide and one molecule of said formaldehyde substance areadded during the reaction; said selenium chelate being present insolution in concentrations exceeding .1 gram per gallon of solution;said lead chelate being the product resulting from the reaction of asoluble lead compound and ethylene diamine tetracetic acid; said leadchelate being present in solution in concentrations exceeding .01 gramper gallon of solution.

2,694,677 Ostrow NOV. 16, 1954 that there is substantially no 2,732,336Ostrow 2,737,485 Overcash et a] OTHER REFERENCES Versenes:

Mass, February 1952, pp. 2-5 (Sec. 1).

Jan. 24, 1956 Mar. 6, 1956 Bersworth Chemical Co., Framingham,

Senderoft Metal Finishing, vol. 48 (July 1950), pp. 59-64; vol. 48(September 1950), pp. 71-78.

Graham et al.: Transactions vol. (1941), pp. 341-354.

Versenes: Bersworth Chemical Co., Mass, February 1952, pp. 46-48 (Sec.2).

Ser. No. 351,241, Weiner (A. P. C.), 18, 1943.

Electrochemical Society,

Framingham,

published May

1. A BATH FOR THE ELECTRODESPOSITION OF COPPER, COMPRISING COPPERCYANIDE IN CONCENTRATIONS RANGING FROM 2.5 TO 16.0 OZ. PER GALLON OFSOLUTION; POTASSIUM CYANIDE IN CONCENTRATIONS RANGING FROM 3.5 TO 25.0OZ PER GALLON OF SOLUTION; POTASSIUM BHYDROXIDE IN CONCENTRATIONSRANGING FROM 2.0 TO 8.0 OZ PER GALLON OF SOLUTION; ROCHELLS SALTS INCONCENTRATIONS RANGING FROM 3.0 TO 12.0 OZ PER GALLON OF SOLUTION; AND ASELENIUM CHELATE; SAID SELENIUM CHELATE BEING THE PRODUCT RESULTING FROMTHE REACTION OF A SOLUBLE SELENIUM COMPOUND WITH THE REACTION PRODUCTOBTAINED BY REATING AN ALIPHATIC AMINE HAVING AT LEAST ONE REPLACEABLEHYDROGEN ATOM ATTACTED DIRECTLY TO AN AMINO NITROGEN ATOM WITH AN ALKALIMETAL CYANIDE AND A FORMALDEHYDEYIELDING SUBSTANCE UNDER CONDITIONSSUFFICIENTLY ALKALINE THAT THERE IS SUBSTANTIALLY NO HYDROLYSIS OF SAIDCYANIDE AND IN TOTAL AMOUNTS SUCH THAT FOR EACH REPLACEABLE HYDROGENATOM ONE MOLECULE OF SAID CYANIDE AND ONE MOLECULE OF SAID FORMALDEHYDESUBSTANCE ARE ADDED DURING THE REACTON; SAID SELENIUM CHELATE BEINGPRESENT IN SOLUTION IN EXCESS OF .1 GRAM PER GALLON OF SOLUTION ANDBEING WITHOUT VALENCE.